As for how long to wait before removing the infertile eggs, it's recommended that you wait at least 14 days after the egg-laying process has completed.
You can generally use the following to assess whether an egg is infertile or not:
Visual Inspection: Take a good look at the eggs. Fertile eggs are more pronounced and appear pinkish in color due to the growth of blood vessels. Infertile eggs, on the other hand, will appear whiter and may have a slight bluish tint.
Candling: Candling involves examining the egg with a strong light source, such as a flashlight, to check its interior. Fertile eggs will show signs of development, such as visible blood vessels and a small embryo. Infertile eggs will remain clear with no signs of growth.
It is important to note that removing the infertile eggs should only be done after carefully assessing each one and ensuring they are not fertile. If you are not comfortable doing this yourself, it's best to consult with a veterinarian or an experienced bird breeder for guidance.
Regarding the reasons for laying so many eggs:
Lovebirds, like many other bird species, have evolved to lay multiple eggs per brood to increase their chances of reproductive success. This is because not all eggs may hatch successfully, and some may be lost due to various factors such as environmental conditions, predators, or accidental breakage.
By laying several eggs, they ensure a higher probability that at least some of the eggs will hatch and the species can continue to thrive and reproduce.